Intervals marked as a standard or regulation requirement are drawn from AS/NZS 3666.2 (microbial control, operation and maintenance), AS 1851-2012 (routine service of fire and smoke control features and kitchen exhaust hoods), AS/NZS 5149.4 as reproduced in the Refrigerant Handling Code of Practice, and the AIRAH kitchen exhaust guideline, as summarised by the industry. AIRAH DA19 schedules and insurer expectations are marked as recommended practice. Section and clause numbers are quoted only where the source states them.
AS 1668 is a design standard. Part 1 sets out how a building's fire and smoke control is engineered, Part 2 how much outdoor air a space needs and how it is delivered. Neither tells an owner how often to service the plant afterwards. Those duties come from four places: AS/NZS 3666.2, which sets the inspection intervals that keep air handling plant free of microbial growth; AS 1851-2012, which carries the fire and smoke control features of the mechanical services and the kitchen exhaust hood into the same routine service regime as the fire systems; AS/NZS 5149.4 and the Ozone Protection legislation, which govern refrigerant leakage and who may touch it; and, for cooling towers, the public health regulation covered in the water systems guide. AIRAH DA19 is the industry's maintenance manual and the source of the service rhythm most contracts quote.
Who does what
Owner and staff tasks are the visual checks, the filter walk on small split systems, the temperature and airflow complaints log and the paperwork. Everything inside the plant is licensed or specialist work: refrigerant may only be handled by a technician holding a refrigerant handling licence, fire and smoke control tests need the fire and mechanical contractors together, kitchen exhaust cleaning is a specialist trade that issues a certificate, and damper inspection needs access panels and a register. The owner or facilities manager remains responsible for the schedule, the records and the annual fire safety statement where the mechanical systems are essential fire safety measures.
Routine inspections, services and tests, by system
Air handling plant and air conditioning (AS/NZS 3666.2)
- Monthly: inspect, and clean or replace where necessary, the outdoor air intakes and exhausts, air filters, humidifiers, coils, trays and sumps, and condensate drains, tundishes and traps.
- Three-monthly: fans; and evaporative cooling equipment including the sump, wetted pads and water strainer.
- Annual: ductwork, terminal units and their coils, and return and relief air grilles.
- Recommended practice (AIRAH DA19 and the library): a quarterly service visit that covers filters, condensate drains and coil condition, a six-monthly outdoor unit and condenser coil clean, and an annual full service with coil cleaning, filter replacement, controls calibration and an outdoor air rate check against the AS 1668.2 design. Split systems in offices commonly run a monthly filter clean by staff and the same quarterly, six-monthly and annual visits.
Refrigerant systems (AS/NZS 5149.4 and the refrigerant licence)
- Per the instruction manual: the standard requires preventive maintenance for leakage at the frequency the system's manual sets.
- Where the manual is silent, the standard's recommended in-service leak inspection frequency: every 12 months for hermetic systems up to 6 kg and for other systems over 3 kg up to 30 kg of refrigerant; every 6 months over 30 kg up to 300 kg; every 3 months over 300 kg; after repair or when leakage is suspected for self-contained and unit systems and for other systems up to 3 kg; stored refrigerant in cylinders every 3 months.
- Always: only a technician holding a refrigerant handling licence may service the system; a system is not recharged until the leak is found, repaired and leak tested; and the charge added is recorded.
The intervals are the standard's recommendation as reproduced in the Australia and New Zealand Refrigerant Handling Code of Practice; the licence requirement is law under the Ozone Protection and Synthetic Greenhouse Gas Management legislation. The code notes that the European F-gas regime, which sets frequencies by carbon dioxide equivalent, is the current best practice reference.
Fire and smoke control features (AS 1851-2012 and AS 1668.1)
- Monthly: the fire trip exercised with the fire indicator panel's monthly test: supply and exhaust fans shut down, stair pressurisation and smoke spill fans start, as the cause and effect matrix requires.
- Three-monthly (recommended practice): run and inspect every fan, check smoke dampers by hand, confirm carpark carbon monoxide controls and access for service.
- Annual: full functional test of the smoke control fans, stair pressurisation, smoke exhaust, fire mode shutdown and controls with detection-triggered operation, using test smoke at the duct probes and the panel's outputs; the cause and effect matrix verified end to end.
- Fire and smoke dampers: a minimum of 20 per cent inspected and cycled each year so every damper is tested within five years, with a damper register kept; a high failure rate in the annual sample brings the remaining dampers forward within twelve months.
- Carpark ventilation: carbon monoxide sensors calibrated annually so the demand control the design relies on keeps working.
In New South Wales mechanical ventilation and smoke control systems are essential fire safety measures on the building's fire safety schedule; the annual test is the evidence behind the annual fire safety statement, and the records sit in the fire logbook beside the AS 1851 fire system records.
Commercial kitchen exhaust (AS 1851-2012 and the AIRAH guideline)
- Weekly to fortnightly: grease filters removed and degreased; weekly for fryers, char-grills and woks.
- Monthly: the hood, canopy body, plenum, filters and accessible duct inspected for excessive grease accumulation; the canopy interior and collection trough degreased.
- Risk-based clean of the duct and fan, at least annually: the standard's minimum is a clean at least once every 12 months. AIRAH's guideline sets the interval from measured grease thickness, an average under 0.2 mm across the system and no point above 2 mm, so a high-volume kitchen cleans monthly or quarterly and a light one every six months. Each clean is certified with photographs.
- Six-monthly: exhaust fan service: blades, bearings, belts and airflow.
- On any change to the cooking line: the fire suppression system over the hood is re-commissioned; see the AS 1851 guide for the suppression intervals.
Insurers commonly make the cleaning certificate a condition of cover for a commercial kitchen, and a grease fire in an uncleaned duct is the claim they decline.
Cooling towers and condenser water
Cooling towers carry their own public health regime: monthly Legionella and colony count testing, a five-yearly risk management plan and an annual independent audit in New South Wales. The water systems testing schedule sets it out; the chiller's condenser water treatment sits on the same monthly rhythm.
What the owner has to keep
The service reports for every visit, with the AS/NZS 3666.2 inspection items ticked and any cleaning noted. The refrigerant service record showing leak inspections, repairs and charge added, by a licensed technician. The damper register with each damper's location, type, last and next inspection. The kitchen exhaust cleaning certificates with grease thickness readings and photographs. The fire trip and smoke control test records in the fire logbook, and in New South Wales the annual fire safety statement that draws on them. Insurers ask for the kitchen and refrigerant records; the fire safety inspector asks for the rest.
Turning the schedule into a register
The intervals above only hold when every air handling unit, split system, exhaust fan, damper group, kitchen hood and smoke control feature in the building is listed with its interval, its contractor and where the report lives. That is an asset register with a maintenance planner on top of it. Standara's library carries these assets with the tasks and intervals attached, so selecting what the building has produces the 12-month schedule, and the compliance report is the record the fire safety inspector, the auditor or the insurer asks for. How to build a facilities asset register covers the site walk; the AS 1851 maintenance schedule covers the fire systems the mechanical services trip.
Related
- AS 1851 maintenance schedule: the fire protection intervals and the NSW record-keeping duty.
- Water systems testing schedule: backflow, TMVs, hot water, cooling towers and grease traps.
- Lift maintenance schedule: lift and escalator servicing, annual inspection and plant registration.
- Electrical testing schedule: RCDs, test and tag, switchboards and emergency lighting.
You now have the service rhythm for the mechanical plant, the rule behind each interval, and the records that prove it.